This application claims priority of Application 20000 269 filed in Finland Feb. 9. 2000.
This invention concerns a web guide in a paper machine or a board machine.
Various web guiding solutions based e.g. on link mechanisms are known in the state of the art. The web guide is a device solution, wherein the web is transferred
in a controlled manner transversely in relation to the machine direction by moving either end of the web guide roller in the machine direction. Thus, the end of the web guide roller includes a transfer mechanism in a state-of-the-art manner. The known web guides are based e.g. on parallel transfers, whereby the end shaft of the roller can be moved in the machine direction by using joint structures and the roller can thus be deflected at its other end, so that its shaft can be placed in an oblique angle in relation to the machine direction. Hereby the web, such as the wire or felt, of the paper machine which is guided on the roller or along it, is transferred laterally towards either the front side or the back of the machine. The distance of motion required in the adjustment is comparatively short, just a few tens of millimeters. The state-of-the-art mechanisms are comparatively complicated and their construction is cumbersome. This means that servicing of the constructions is difficult.
In the known web guides, the transfer mechanisms transfer the transferable pivoted shaft of the guiding roller along an arc of a circle. This causes problems in doctoring of the roller, because the doctor beam must then be able to turn in its lengthwise direction for the doctoring to take place reliably.
There are e.g. bellows mechanisms known in the state of the art, whereby with the aid of air pressure supplied into the bellows a force is directed at a lever structure, and the shaft stub of a guiding roller attached to the lever mechanism is thus affected.
The known device solutions are not either suitable for all positions. This is so because the roller guide may be located in such a way that the web travels vertically upwards, whereby the web guide roller is located on the said run of web and the force of gravity is applied in different ways to supporting bearing constructions than in horizontal positions.
This application presents a new type of guide structure for use in a paper machine or in a board machine, wherein the essential feature is the use of a bearing housing as the rolling element. Thus, at least one shaft stub of the web guide roller includes such a bearing structure, wherein the bearing housing is adapted to roll against a stop face. To bring about rolling, an actuator is used, which connects with the bearing housing, so that by using the actuator the bearing housing may be rotated along its stop face in the desired direction. Either one actuator or two actuators may be used in the invention to move the bearing housing, whereby if one actuator is used, the return motion and a counterforce may be achieved e.g. by using a spring. Another purpose of the actuator is to keep the rolling surface of the bearing housing firmly against the stop face.
In the guide solution according to the invention, the guide is thus replaced e.g. with a cylindrical bearing housing of the roller. Such an embodiment is also possible, wherein the curvature of only a certain area and angular sector of the bearing housing is utilised.
In the guide solution according to the invention, a separate rolling surface and a separate actuator unit can be connected to the bearing housing. Hereby the guide according to the invention is especially suitable for already existing guiding rollers. The existing guide is hereby removed and the solution according to the invention is installed in one bearing of the guiding roller, and a sliding surface, unless such a surface does not already exist, is installed in the frame structure of the paper machine/board machine.
The bearing housing acting as a guide is moved by either one actuator or by two actuators, which may be a hydraulic/pneumatic cylinder/air bellows/mechanical conveyor screw.
The bearing housing rolls along the base in a linear motion. Should electric/hydraulic/pneumatic power failures occur, the roller will remain in its place supported by the base.
The following is a presentation by way of summary of the advantages achieved through the device solution according to the invention: the guide is
reliable in operation
contains no sliding surfaces
friction-free owing to the rolling motion
it needs very little space, since only the actuator needs space
few components, whereby the construction is advantageous
linear motion
contains no wearing components requiring service
doctoring of the roller takes place reliably.